In the hose fitting art, such as in pressurized hydraulic systems, tubular fittings are associated with the hose for permitting the hose to be attached to conduit components. The usual fitting construction includes a tubular nipple received within the hose bore, and the outer end of the nipple includes threads or other configurations whereby the nipple may be connected to other components of the system. The fitting often includes an annular socket circumscribing the hose mounted upon the nipple, and the socket may be inwardly crimped upon the nipple mounted hose to assure a fluid tight interconnection between the hose and nipple, and produce a mechanical interconnection capable of withstanding high tension forces. It is known to utilize mating elements between the socket and nipple to align and maintain the assembly of these components.
Examples of typical pressurized system hose end fittings are shown in U.S. Pat. Nos. 2,768,009; 3,539,207; 3,589,752 3,711,131 and 3,990,728.
Further, it is known to construct hose of a convoluted form wherein helical convolutions are defined within the hose for the purpose of improving hose flexibility and strength. Reinforcing elements may be associated with the convolutions. Fittings employed with convoluted hose have utilized spiral projections or threads defined upon a tubular nipple wherein the nipple convolutions correspond with those of the hose and the fitting is "threaded" into the hose bore. Fittings of this type are to be found in U.S. Pat. No. 3,078,109; 3,381,981 and 3,992,044. Because of the presence of the the hose convolutions, difficulty has been encountered in maintaining a fluid tight seal between convoluted hose and its associated fittings. Such difficulties are especially present when endeavoring to mount an end fitting upon convoluted hose utilizing polymerized tetrafluoroethylene such as commonly sold under the trademark "Teflon". Because of the lubricity and physical characteristics of Teflon inner tube hose considerable difficulty has been encountered in producing an acceptable end fitting for hose of such construction.
It is an object of the invention to provide a hose end fitting for hose having a convoluted inner tube wherein the fitting is of economical construction, readily accepts the hose upon a tubular nipple, and produces an effective fluid tight interconnection with the hose capable of withstanding high tension forces.
Another object of the invention is to produce a hose end fitting particularly suitable for hose having a synthetic plastic inner tube, the fitting utilizing a swaged socket, and the socket being of such configuration to cooperate with the nipple shape to improve sealing and tension characteristics, and wherein a high strength mechanical interconnection between the fitting nipple body and socket is achieved.
Yet another object of the invention is to provide a hose end fitting employing a swaged socket which is mechanically related to a nipple body, and wherein a rotatable nut mounted upon the nipple body will not inadvertently engage the socket, or interfere therewith, assuring uniform connection nut operation.
In the practice of the invention a tubular body includes a nipple having an outer surface upon which a helical projection is defined which is adapted to be threaded into the helical bore of a synthetic plastic convoluted hose inner tube. The helical nipple projection corresponds to the pitch of the hose helices, and an annular socket compresses the hose upon the nipple. The socket includes a tang which is radially received within a groove defined in the nipple to prevent axial displacement between nipple and socket, and inwardly projecting annular serrations are defined upon the socket inner surface for compressing the hose at specific locations.
The nipple outer surface receiving the hose also includes shaped sealing surfaces and grooves related to the socket serrations, and the nipple outer surface includes a "ramp" configuration having an increased diameter in the direction of the nipple hose receiving end which effectively resists tension forces interposed between the nipple and hose.
In a fitting utilizing a rotatably mounted connector nut upon the nipple the cooperating nipple and nut lands are so axially dimensioned as to prevent the socket from interferring with the nut operation, and the disclosed construction simplifies this type of hose end fitting as compared with fittings presently available for use with convoluted hose.